Above: Even offshore wind results in a greater environmental impact than nuclear licence renewal One was solar PV, for which the assessment assumed a


capacity factor of 25%, requiring 7,600 MWe of solar capacity covering 47,000 acres of land (19,000 ha). Dominion is already pursuing an “aggressive” strategy on PV, so NRC staff said acquiring land would be difficult. Alternatively, the staff considered replacing North Anna with wind power. In this case, it assumed a capacity factor of 40% for onshore wind, which would require 4,750 MW of wind capacity. But it noted that Virginia currently has no installed utility-scale wind farms and only limited onshore wind potential. It also considered using offshore wind, for which NRC staff assumed a higher capacity factor of 50%. That brought the capacity required down to 3,800 MW, but it would still require 230,000 acres (93,000 Ha), which NRC staff says exceeds the area of the Federal waters off coastal Virginia that is designated for wind energy leasing. As with solar PV, Dominion is already pursuing offshore wind and so acquiring additional lease areas would also be difficult. Other offshore options (wave and tidal power) were considered to be immature technologies. Other alternatives to licence renewal fall foul of the


Virginia Clean Energy Act (VCEA), which came into effect in 2020 and which mandates the retirement of all generation that emits carbon dioxide as a byproduct of combustion by 2045. Oil, coal and gas-fired power stations would be unlikely to be granted permits and the NRC staff said that although some gas-fired generation will be on the system, it will be used to manage renewables rather than as a replacement baseload power alternative. The VCEA would also outlaw meeting demand by extending the lifetime of fossil plants. Smaller alternatives – biomass or waste to energy – hit


several barriers. Dominion has plants of both types but rated around the 50 MW level. The NRC staff said building 38 new plants was unlikely and in addition both fall foul of VCEA and both options raise questions over fuel supply. Virginia’s natural resources do not include significant


geothermal sites and although it has one of the US’s largest hydropower storage sites (the 3,000 MW Bath County pumped storage station) hydropower is complicated by “the competing demands for water resources, and public opposition to the environmental impacts from the construction of large hydroelectric power facilities”. The NRC staff also dismissed ‘no-build’ options such as demand-side management (saying it could not guarantee reductions in electricity demand) and buying-in power (saying it was typically more expensive than self-generated power and carried a risk of non-delivery).


Finally, the NRC staff also considered fuel cells, which


they said had economic and technological barriers. For technology, the staff considered that fuel cell units used for power production are likely to be as small as 10 MW, so nearly 200 units would be required. They were not competitive on cost, at $6,639 per kilowatt, and staff thought that cost may not fall, despite government initiatives.


Viable alternatives Having dismissed most of the alternatives, the NRC staff considered two “reasonable” options: replacing the two existing North Anna units with five SMRs; and a combination of carbon-free replacement power generation technologies with demand-side management. The staff considered light water SMRs, noting that their


small size allows for several SMRs to be bundled in a single containment for greater siting flexibility, because they can fit in locations not large enough to accommodate a conventional nuclear reactor. To replace North Anna, they assumed an array of four


400 MWe SMRs (using a generic design and representative construction and operating parameters derived from several commercial designs) and one 300 MW SMR to fully replace the site capacity. This could be built in a 200 acre (81 Ha) area west of and adjacent to the existing North Anna facilities which has already been evaluated during permitting processes. The NRC staff’s second option is mixed capacity. It would


combine 800 MW of solar PV (from eight 400 MW solar farms operating at 25% capacity factor), 500 MW of offshore wind (from 72 14 MW turbines along Virginia’s Atlantic coast and in Chesapeake Bay, together providing 1000 MW of capacity and operating at 50% capacity factor), 400 MWe from an SMR on the North Anna site and 200 MW from demand-side management, although that combination could be adjusted. Around 20,000 acres (8,000 Ha) of land would be


required to operate the eight solar power and storage facilities. The offshore wind component would require around 72 square nautical miles, once space is allowed for separation to avoid inter-turbine air turbulence and allow for navigation by ocean vessels. There would be additional disturbance from trenching activities required to install cable to connect the turbines and export the power to onshore facilities, although that could be shared, given that Dominion already has plans for 5GW of offshore wind over the next 15 years.


www.neimagazine.com | September 2024 | 39


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